Background Low-temperature solders are considered eco-friendly because of lowered wasted power, warpage, electromigration. In addition, chips are becoming increasingly integrated so as to achieve superior performance. Semiconductor packaging has moved from two-dimensional to three-dimensional integrated-circuits with vertical stacking for increased functionality. Thermal budget impacts electronic device manufacture, specifically in heterogeneous integration. Therefore, reduction of process temperatures is necessary.
Methods Bi and In were selected in this study because they are commercial solders with low-melting points. Further, the microstructures and interfacial reactions of Bi–In solders have not been extensively studied. This study entailed a systematic examination of the interfacial reactions occurring between Bi67In and Cu metallization upon reflow and subsequent aging was performed.
Findings It was observed that In segregates in the middle region of Cu11In9 after reflow. The phase transformations from Cu11In9 to CuIn2 start in the In segregation region. This remarkable phenomenon warrants in-depth research.
Relation:
Journal of the Taiwan Institute of Chemical Engineers 151, 105099
